Road planing is the practice of removing an upper layer of paving material from a traffic bearing substrate forming a road. Paving material used in road construction tends to deteriorate over time as a result of weathering, traffic wear, fatigue, biological processes and still other factors. It is common practice for new “lifts” of paving material to be paved upon older, worn layers. Eventually, however, it becomes impractical to build the road any higher, and some or all of the road needs to be rebuilt. Cold planers are commonly used to cut old paving material from the traffic bearing substrate to enable the placement of new paving material on top.
A typical cold planer is a self-propelled machine or attachment to a self-propelled machine that includes a cutting mechanism configured to remove paving material to some specified depth, rendering a more or less planar surface to serve as a grade upon which a new mat of paving material is to be placed. The process of cold planing tends to be fairly demanding, as substantial energy may be required to cut the relatively hard and dense substrate, then elevate the cut material to a conveyor for off-loading from the cold planer. It will thus be readily understood that the service environment of cold planers tends to be harsh, and the components of such machines subjected to quite demanding conditions.
Among other challenges, in certain instances the cutting mechanism of a cold planer may break off relatively large slabs of paving material which the conveyor and other sub-systems have difficulty in handling. U.S. Pat. No. 4,221,434 to Swisher, Jr. et al. is directed to a Roadway Breaker Plate For A Planar Apparatus, in which a drum type planer cutter removes a top portion of an existing roadway. The breaker plate appears to provide a counteracting shearing force on the top portion of the roadway at a predetermined distance from the planer cutter, to remove cuttings from the roadway of purportedly uniform size. The design proposed by Swisher, Jr. et al. may work well for certain cold planer designs, but there is always room for improvement and broadened applicability.